The objectives of this proposal are to continue and to extend the development of our radiosotopic methods for the quantification of myocardial infarction and for the evaluation of therapeutic interventions to protect ischemic myocardium and to limit ultimate infarct size. We propose to assess the utility of three separate methods for these purposes in experimental animals; one to assess the short-term effects of interventions (over the first 24 hours) utilizing serial imaging with Tc99m-glucoheptonate; another to evaluate the intermediate term results (3-7 days) utilizing a dual radiopharmaceutical approach with Tc99m-glucoheptonate and Tc99m-pyrophosphate; and finally a method that has the potential of following the effects of interventions from the time of infarction to several months or years afterwards, utilizing a quantitative method of measuring changes in left ventricular wall motion and regional myocardial function. Each of the methods proposed is simple, safe and noninvasive and entirely applicable to patients in the emergency room, coronary care unit or out-patient setting - and will be applied to patients as a major part of this proposal. In addition, we will conduct basic research on three levels so that improvements and refinements in our methodology for quantitating infarct size and non-invasively determining the effects of intervention can be achieved. Firstly, we will study the distribution of these radiopharmaceuticals in the isolated rabbit heart in an attempt to derive further information about their behavior at the tissue level; secondly, we will extend and refine our mathematical models describing the kinetics and distribution dynamics of infarct growth using radiopharmaceuticals; and thirdly, we will continue to develop computerized methods of reconstructing the 3-dimensional structure of myocardial infarcts from several 2-dimensional imaging projections.